Day 26 - OMG WTF? Season finale
It had been my understanding that Philip Glenister didn't want to do a third series of Ashes to Ashes, so the cliffhanger ending of 2.08 took me completely by surprise at the time. Only later did I learn that a third series had been commissioned.
Something similar happened with Nurse Jackie. I thoroughly enjoyed this show, but the final episode (or so I thought) ended in chaos. It all but killed my love for the series, until I read on IMDb that there was going to be a second season. (And, as I now see, a third one as well. How silly of me to think they would quit so soon!) Anyway, looking forward to it.